feat: add DisableTargetIdentityInsertTables for tables where target has no identity

- Add per-table config DisableTargetIdentityInsertTables; when true, merge
  skips IDENTITY_INSERT (for target without identity column, source with).
- Thread setting through SyncJobConfig, SyncJobTable, TableSchema and
  GetNewOrUpdatedMergeStatement.
- Document in README (config table + note).
- Suppress Azure SDK diagnostic logs in host.json (Azure.Core/Azure → Error).
- Use collection expression for empty Tables in ProcessSyncJobService.

Author: devlead

README.md

@@ -32,12 +32,15 @@ The function is configured through Azure App Settings / Environment variables, y
 | `SyncJobsConfig__Jobs__[key]__Manual`                               | Flag is sync excluded from schedules      | `true`                                                                       |
 | `SyncJobsConfig__Jobs__[key]__Schedules__[key]`                     | Optional opt-in/out schedules             | `true`                                                                       |
 | `SyncJobsConfig__Jobs__[key]__Tables__[key]`                        | Fully qualified name of table to sync     | `dbo.MyTable`                                                                |
+| `SyncJobsConfig__Jobs__[key]__DisableTargetIdentityInsertTables__[key]` | Optional, per table. When `true`, merge does not use `IDENTITY_INSERT` on target (use when target has no identity column but source does). | `true` or `false` |
 
 
 > Note:
 >
 > Replace `[key]` with unique name of sync job / table config i.e. `MySync` / `MyTable` would result in `SyncJobsConfig__Jobs__MySync__Tables__MyTable`=`dbo.MyTable`
 >
+> **DisableTargetIdentityInsertTables**: Omit or set to `false` to copy identity values from source (default). Set to `true` per table when the target schema has no identity column but the source does.
+>
 > Configuration from KeyVault replace `__` with `--` i.e. `SyncJobsConfig--Jobs--MySync--Tables--MyTable`
 
 ## Schedules

src/SqlBulkSyncFunction/Helpers/SqlStatementExtensions.cs

@@ -53,9 +53,9 @@ DROP TABLE {0}
                 tableName
                 );
 
-        public static string GetNewOrUpdatedMergeStatement(this TableSchema tableSchema)
+        public static string GetNewOrUpdatedMergeStatement(this TableSchema tableSchema, bool disableTargetIdentityInsert)
         {
-            var identityInsert = tableSchema.Columns.Any(column => column.IsIdentity);
+            var identityInsert = !disableTargetIdentityInsert && tableSchema.Columns.Any(column => column.IsIdentity);
             var statement = string.Format(
                 @"{6};
 MERGE {0} AS target

src/SqlBulkSyncFunction/Helpers/SyncJobConfigExtensions.cs

@@ -36,16 +36,23 @@ private static SyncJobTable[] ToSyncJobTables(this SyncJobConfig job)
                 StringComparer.OrdinalIgnoreCase
             );
 
-            return job.Tables.Select(
+            var disableTargetIdentityInsertTables = job.DisableTargetIdentityInsertTables?.ToLookup(
+                key => key.Key,
+                value => value.Value,
+                StringComparer.OrdinalIgnoreCase
+            );
+
+            return [.. job.Tables.Select(
                 sourceTable => new SyncJobTable(
                     sourceTable.Value,
                     targetTableLookup?[sourceTable.Key].FirstOrDefault() switch
                     {
                         { Length: > 0 } overrideTargetTable => overrideTargetTable,
                         _ => sourceTable.Value
-                    }
+                    },
+                    disableTargetIdentityInsertTables?[sourceTable.Key].FirstOrDefault() ?? false
                 )
-            ).ToArray();
+            )];
         }
 
         private static string TryGetToken(SyncJobConfigDataSource dataSource, ConcurrentDictionary<string, string> tokenCache) => dataSource.ManagedIdentity && tokenCache.TryGetValue(dataSource.TenantId ?? string.Empty, out var sourceToken)

src/SqlBulkSyncFunction/Models/Job/SyncJobConfig.cs

@@ -8,6 +8,7 @@ public record SyncJobConfig
         public SyncJobConfigDataSource Target { get; init; }
         public Dictionary<string, string> Tables { get; init; }
         public Dictionary<string, string> TargetTables { get; init; }
+        public Dictionary<string, bool> DisableTargetIdentityInsertTables { get; init; }
         public int? BatchSize { get; init; }
         public string Area { get; init; }
         public bool? Manual { get; init; }

src/SqlBulkSyncFunction/Models/Job/SyncJobTable.cs

@@ -1,4 +1,4 @@
 namespace SqlBulkSyncFunction.Models.Job
 {
-    public record SyncJobTable(string Source, string Target);
+    public record SyncJobTable(string Source, string Target, bool DisableTargetIdentityInsert);
 }

src/SqlBulkSyncFunction/Models/Schema/TableSchema.cs

@@ -27,6 +27,7 @@ public record TableSchema
         public TableVersion SourceVersion { get; }
         public TableVersion TargetVersion { get; }
         public int BatchSize { get; }
+        public bool DisableTargetIdentityInsert { get; }
         private TableSchema(
             SyncJobTable table,
             Column[] columns,
@@ -45,6 +46,7 @@ private TableSchema(
 
             SourceTableName = table.Source;
             TargetTableName = table.Target;
+            DisableTargetIdentityInsert = table.DisableTargetIdentityInsert;
             SyncNewOrUpdatedTableName = FormattableString.Invariant($"sync.[{bufferName}_{DateTime.UtcNow:yyyyMMdd}_{targetVersion.CurrentVersion:00000000}_NewOrUpdated]");
             SyncDeletedTableName = FormattableString.Invariant($"sync.[{bufferName}_{DateTime.UtcNow:yyyyMMdd}_{targetVersion.CurrentVersion:00000000}_DeletedTable]");
             Columns = columns;
@@ -57,7 +59,7 @@ private TableSchema(
             SourceNewOrUpdatedSelectStatement = this.GetNewOrUpdatedAtSourceSelectStatement();
             SourceSelectAllStatement = this.GetSourceSelectAllStatement();
             SourceDeletedSelectStatement = this.GetDeletedAtSourceSelectStatement();
-            MergeNewOrUpdateStatement = this.GetNewOrUpdatedMergeStatement();
+            MergeNewOrUpdateStatement = this.GetNewOrUpdatedMergeStatement(DisableTargetIdentityInsert);
             DeleteStatement = this.GetDeleteStatement();
             DropNewOrUpdatedTableStatement = SyncNewOrUpdatedTableName.GetDropStatement();
             DropDeletedTableStatement = SyncDeletedTableName.GetDropStatement();

src/SqlBulkSyncFunction/Services/ProcessSyncJobService.cs

@@ -51,8 +51,7 @@ public async Task ProcessSyncJob(SyncJob syncJob, bool globalChangeTracking)
                 Logger.LogInformation("{Scope} Fetching table schemas...", scope);
                 var schemaStopWatch = Stopwatch.StartNew();
                 var tableSchemas = (
-                        syncJob.Tables
-                        ?? Array.Empty<SyncJobTable>()
+                        syncJob.Tables ?? []
                     )
                     .Select(
                         table => TableSchema.LoadSchema(

src/SqlBulkSyncFunction/host.json

@@ -6,7 +6,9 @@
         "default": "Warning",
         "Host.Results": "Warning",
         "Function": "Warning",
-        "Host.Aggregator": "Warning"
+        "Host.Aggregator": "Warning",
+        "Azure.Core": "Error",
+        "Azure": "Error"
     },
     "applicationInsights": {
       "samplingSettings": {